Emergency services were called on Wednesday afternoon after reports of a gas explosion and fire at the three-storey townhouse in the Scottish capital.

Lothian and Borders police said the bodies of two boys and a girl of primary school age had been found inside while their 46-year-old mother was discovered on the ground outside.

She had “exited” from the second floor and is in hospital with serious injuries, Detective Superintendent Allan Jones said. Her condition is said to be stable.

“The circumstances ... would suggest that the children have died in suspicious circumstances, and that is the nature of the investigation,” Jones told reporters.

He said it was too early to say what the cause of death was and detectives were awaiting post mortem reports.

However, officers had found little evidence of fire damage and nothing to suggest there had been an explosion, or fault with the gas supply.

“I can only say that the injuries at this moment are suspicious,” Jones said.

Police said the family had been reported missing from their home in the Aberdeen area and were traced to the house in Edinburgh last month where they were found to be safe and well.

Media reports said the mother and father, who lives in the Aberdeen area, were going through divorce proceedings.

Jones confirmed the couple, who came to Scotland from the United States 13 years ago, had been due to take part in “civil proceedings” on Tuesday.

“There is a separation between mother and father at the moment,” he said. “It’s very early at present. We will need to look into the background of that, that’s clearly significant to the investigation.”

He said what the mother and children had been doing in Edinburgh was a “dark area” and they needed more information about their movements in the last few weeks.

Detectives had not been able to speak to the children’s mother as she was sedated.

“We’re not in a position that we can speak to her as yet,” Allan said. “We would like to do that to get a true background to the events of yesterday and find out exactly what happened within the house.”